The present invention relates to a 3D data analysis apparatus and a 3D data analysis method. More specifically, the present invention relates to a 3D data analysis apparatus and the like capable of specifying microparticles to be analyzed in a 3D stereoscopic image.
To analyze microparticles including biologically relevant particles such as cells, microbes, and liposomes and synthetic particles such as latex particles, gel particles, and particles for industrial use, a microparticle measurement apparatus is used which introduces a dispersion liquid of microparticles in a flow channel and measures the microparticles optically, electrically, or magnetically.
As an example, there is a particle analyzer that distinguishes synthetic particles on the basis of sizes or shapes. Examples of a parameter (variable) which can be measured by the particle analyzer include an elemental composition and a particle diameter of a microparticle.
Further, to analyze biologically relevant particles, a flow cytometer (flow cytometry) is used. Examples of a parameter which can be measured by the flow cytometer include forward scattered light (FS), side scatter (SS), fluorescent light (FL), and impedance of microparticles. The forward scattered light (FS), the side scatter (SS), and the fluorescent light (FL) are used as parameters that indicate an optical characteristic of a cell or a microbe (hereinafter, simply referred to as “cell”), and the impedance is used as a parameter that indicates an electrical characteristic of a cell.
Specifically, first, the forward scattered light is light that is scattered at a small angle in a forward direction with respect to an axis of laser light and includes scattered light, diffracted light, and refracted light of laser light which is generated on a surface of a cell. The forward scattered light is mainly used as a parameter that indicates the size of a cell. Next, the side scatter is light that is scattered at approximately 90 degrees with respect to an axis of laser light and is scattered light of laser light that is generated in a granule or a core inside a cell. The side scatter is mainly used as a parameter that indicates an internal structure of a cell. Further, the fluorescent light is light that is generated from a fluorochrome labeled to a cell and is used as a parameter that indicates existence or nonexistence of a cell surface antigen recognized by a fluorochrome-labeled antibody, the amount of a nucleic acid to which a fluorochrome is combined, or the like. Furthermore, the impedance is measured by an electrical resistance method and used as a parameter that indicates a cell volume.
To analyze measurement data in a flow cytometer, a data analysis apparatus is used in which measurement values of cells are plotted with these measurement parameters being as axes, thereby creating a diagram that shows a characteristic distribution of the cells in a cell population. A one-dimensional distribution chart with the use of one measurement parameter is called as a histogram, which is created with an X axis indicating the measurement parameter, and a Y axis indicating the number of cells (count). Further, a two-dimensional distribution chart in which two measurement parameters are used is called as a cytogram, which is created by plotting cells on the basis of the measurement values in a coordinate plane with the X axis indicating one measurement parameter and the Y axis indicating the other measurement parameter.
The cell population as a sample includes unnecessary cells not to be analyzed, so the analysis of the measurement data is performed after a cell small population to be analyzed is selected from the cell population as the sample. The cell small population to be analyzed is selected by specifying an area in which the cell small population exists on the histogram or the cytogram. This operation is called as “gating” because cells as targets are enclosed in an area specified on the histogram or the cytogram.
On the histogram with one measurement parameter as an axis or on the cytogram with one combined measurement parameter as axes, the cell small population to be analyzed and unnecessary cells may exist in an overlapped area in some cases. For example, when a lymphocyte is analyzed with human peripheral blood as a sample, on a cytogram with a forward scattered light (FS) and a side scatter (SS) used for axes, a part of monocyte exists in the same area as the lymphocyte in some cases. Therefore, when performing gating, a user has to specify an area in which only lymphocyte exists so as not to enclose the monocyte.
In order to specify an area so that only a cell small population to be analyzed is enclosed without enclosing unnecessary cells, conventionally, a user has to perform gating while referring to a plurality of histograms or cytograms. Along with improvement of the performance of a flow cytometer, the number of parameters that can be measured is increased, so the user has to refer to more histograms or cytograms. Further, at this time, the user is requested to perform a gating operation while imaging a three-dimensional distribution chart (3D distribution chart) in which two cytograms are combined.
To assist the user in performing the gating operation, Patent Document 1 proposes “an analysis apparatus including a measurement data obtaining means for obtaining first, second, and third measurement data items from an analyte, a 3D distribution chart creating means for creating a 3D distribution chart that indicates a distribution of formed elements contained in the analyte with the first, second, and third measurement data items as axes, an area setting means for variably setting a separate area on the 3D distribution chart, and a reference distribution chart creating means for creating, with respect to formed elements that belongs to the separate area set by the area setting means, at least one of a 2D distribution chart with the first and second measurement data items used as the axes and a frequency distribution chart with the first measurement data item used as the axis” (see, claim 9 of Patent Document 1). By the analysis apparatus, it is possible to set the separate area on the 3D distribution chart while referring to the 2D distribution chart (cytogram) and the frequency distribution chart (histogram) displayed along with the 3D distribution chart. It should be noted that the 3D distribution chart of the analysis apparatus is not viewed stereoscopically but is displayed two-dimensionally on a display.
In relation to the present invention, twin-lens stereo image technology (3D stereoscopic image technology) will be described. In the twin-lens stereo image, first, two images when an object is viewed with a right eye and a left eye are prepared. Then, these images are displayed at the same time, and an image for the right eye is presented only to the right eye, and an image for the left eye is presented only to the left eye. As a result, an image that appears in the eyes at a time when the object is viewed in a 3D space is reproduced, and a user is caused to stereoscopically view the object.
For a 3D display which allows a stereoscopic view, a (a) glasses type, a (b) glasses-free type, and a (c) viewer type are mainly adopted. The (a) glasses type includes an anaglyph type, a polarization filter type, and a time-sharing type. Further, the (b) glasses-free type includes a parallax barrier type and a lenticular type, and the (c) viewer type includes a stereoscope type and a head mount type.